<html>
<head>
<meta charset="utf-8">
<script type="application/x-javascript" src="../util.js"></script>
<script>
var processor = {
  lastTime : new Date,
  timerCallback: function() {
    if (this.video.paused || this.video.ended) {
      return;
    }
    this.computeFrame();
    var t = new Date;
    var elapsed = t - this.lastTime;
    this.lastTime = t;
    var self = this;
    setTimeout(function () {
        self.timerCallback();
      }, Math.max(0, 33-elapsed));
  },

  init: function() {
    if (this.initDone) return;
    this.c2 = document.getElementById("c2");
    this.ctx2 = getGLContext(this.c2);
    this.greenScreen = new Filter(this.ctx2, 'identity-flip-vert', 'greenScreen');
    this.ctx2.activeTexture(this.ctx2.TEXTURE0);
    this.tex = loadTexture(this.ctx2, this.c1, false);
    this.ctx2.activeTexture(this.ctx2.TEXTURE1);
    this.tex2 = loadTexture(this.ctx2, document.getElementById('i'), false);
    this.ctx2.activeTexture(this.ctx2.TEXTURE0);
    this.initDone = true;
  },

  doLoad: function() {
    this.video = document.getElementById("video");
    this.c1 = document.getElementById("c1");
    this.ctx1 = this.c1.getContext("2d");
    this.ctx1.globalCompositeOperation = 'copy';
    this.ctx1.fillRect(0,0,this.c1.width, this.c1.height);
    var self = this;
    this.video.addEventListener("play", function() {
        self.init();
        self.width = self.video.videoWidth;
        self.height = self.video.videoHeight;
        self.lastTime = new Date;
        self.timerCallback();
      }, false);
  },

  computeFrame: function() {
//     this.ctx1.drawImage(this.video, 0, 0, this.width, this.height);
    this.ctx2.texImage2D(this.ctx2.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, this.video);
    this.greenScreen.apply(function(s) {
        s.uniform1i('Texture', 0);
        s.uniform1i('Texture2', 1);
    });

    return;
  }
};

</script>
<script id="identity-flip-vert" type="x-shader/x-vertex">
    attribute vec3 Vertex;
    attribute vec2 Tex;

    varying vec4 texCoord0;
    void main()
    {
        texCoord0 = vec4(Tex.s,1.0-Tex.t,0.0,0.0);
        gl_Position = vec4(Vertex, 1.0);
    }
</script>
<script id="greenScreen" type="x-shader/x-fragment">
    precision mediump float;

    uniform sampler2D Texture;
    uniform sampler2D Texture2;

    varying vec4 texCoord0;
    void main()
    {
        vec4 c = texture2D(Texture, texCoord0.st);
        float r = c.r * 0.5;
        float a = c.g * 6.28;
        float x = cos(a) * r;
        float y = sin(a) * r;
        vec4 c2 = texture2D(Texture2, vec2(0.7+x, 0.5+y));
        // Shaders with branches are not allowed when dealing with non-SOP content
        // so instead of "if (b) c2.a = 0;", we use mix()
        bool b = (c.g > 120.0/255.0 && c.r > 120.0/255.0 && c.b < 50.0/255.0);
        c2.a = mix(c2.a, 0.0, float(b));
        gl_FragColor = c2;
    }
</script>
    <style>
      body {
        background: black;
        color:#CCCCCC;
      }
      a {
          color: white;
      }
      #c2 {
        background-image: url(http://www.mozbox.org/pub/green/foo.png);
        background-repeat: repeat;
      }
      div {
        float: left;
        border :1px solid #444444;
        padding:10px;
        margin: 10px;
        background:#3B3B3B;
      }
      img { display: none; }
    </style>
 </head>
  <body onload="processor.doLoad()">
    <div>
        This is a port of Paul Rouget's <a href="http://blog.mozbox.org/post/2009/02/25/video-canvas%3A-special-effects">Canvas+Video green screen demo</a>, plus a texture lookup from the Firefox logo based on the values of the green and red color channels.
    </div>
    <div>
      <video id="video" controls="true">
        <source src="http://www.mozbox.org/pub/green/video.ogv"></source>
        <source src="http://cs.helsinki.fi/u/ilmarihe/c3d/demos/video.mp4"></source>
      </video>
      <canvas id="c1" width="320" height="192"></canvas>
    </div>
    <div>
      <canvas id="c2" width="640" height="384"></canvas>
    </div>
    <img id="i" src="http://www.mozbox.org/pub/green/foo.png">
  </body>
</html>
